[PATCH v2 1/2] f2fs: quota: do not use GFP_NOFS in f2fs_quota_read()
From: Chao Yu
Date: Tue Jul 07 2026 - 07:45:42 EST
Commit 02117b8ae9c0 ("f2fs: Set GF_NOFS in read_cache_page_gfp while doing
f2fs_quota_read") adds GFP_NOFS in f2fs_quota_read() to avoid below deadlock:
- do_sys_open
- vfs_open
- dquot_file_open
- dquot_initialize
- dqget
- dquot_acquire
: locks &dqopt->dqio_mutex (VFS Quota Mutex)
- qtree_read_dquot
- f2fs_quota_read
- read_mapping_page (GFP_KERNEL / allows GFP_FS)
- __alloc_pages_nodemask
- try_to_free_pages (Direct Reclaim)
- prune_icache_sb
- evict
- f2fs_evict_inode
- dquot_drop
- dqput
- dquot_commit
: tries to lock &dqopt->dqio_mutex again
==> DEADLOCK (waiting for itself)
As Jan Kara mentioned, quota system has fixed this issue w/ commit
537e11cdc7a6 ("quota: Prevent memory allocation recursion while holding
dq_lock"), so this GFP_NOFS flag should be relic, let's use GFP_KERNEL
instead.
Cc: Jan Kara <jack@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
v2:
- fix to use GFP_KERNEL instead of 0.
fs/f2fs/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index da468df058eb..b1725ca68010 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3168,7 +3168,7 @@ static ssize_t f2fs_quota_read(struct super_block *sb, int type, char *data,
repeat:
folio = mapping_read_folio_gfp(mapping, off >> PAGE_SHIFT,
- GFP_NOFS);
+ GFP_KERNEL);
if (IS_ERR(folio)) {
if (PTR_ERR(folio) == -ENOMEM) {
memalloc_retry_wait(GFP_NOFS);
--
2.49.0